Boar’s Head, the deli meat company at the center of a deadly listeria food poisoning outbreak, is being scrutinized by law enforcement officials, the U.S. Department of Agriculture disclosed in response to government records requests.

Officials with the USDA’s Food Safety and Inspection Service refused to share documents regarding the agency’s inspections and enforcement at the Boar’s Head plant in Jarratt, Virginia, and inspection reports from eight other company factories across the U.S.

The records — which FSIS acknowledged include dozens of pages of documentation — were withheld because they were compiled “for a law enforcement purpose, which includes both civil and criminal statutes,” according to a letter sent Friday in response to Freedom of Information Act requests submitted by the Associated Press. Releasing the records could “interfere with” and “hinder” the government’s investigation, the letter said.

The AP asked for records regarding the listeria outbreak that, according to the U.S. Centers for Disease Control and Prevention, has killed 10 people and sickened at least 50 in 19 states since May. Listeria bacteria were initially detected in samples of Boar’s Head liverwurst and later traced to illnesses in people.

Previously released records revealed problems including mold, insects, dripping water, and meat and fat residue on walls, floors and equipment dating back at least two years. Boar’s Head earlier recalled more than 7 million pounds of deli meat distributed to stores across the country. This month, the Sarasota, Florida-based company said it has closed the Virginia plant and permanently stopped making liverwurst.

Boar’s Head is facing several lawsuits filed by victims and their families.

The problem was discovered when a Boar’s Head liverwurst sample collected by health officials in Maryland tested positive for listeria. Further testing showed the type of bacteria was the same strain causing illnesses in people.

FSIS officials did not respond to AP’s emails seeking additional comment about the records. Justice Department officials declined to comment on potential legal actions against Boar’s Head.

This week, Sen. Richard Blumenthal and Rep. Rosa DeLauro called on the Agriculture and Justice departments to determine whether to bring criminal charges against Boar’s Head. In response, the USDA’s own internal investigators are reviewing the agency’s work and will decide by the end of the year whether to open an inquiry, according to Blumenthal’s office.

Past food poisoning outbreaks have resulted in criminal and civil penalties.

In 2020, Chipotle agreed to pay a record $25 million to resolve criminal charges over tainted food that sickened more than 1,100 people in outbreaks from 2015 to 2018. In 2015, former Peanut Corporation of America executive Stewart Parnell was sentenced to 28 years in prison after an outbreak of salmonella in his company’s peanut butter killed nine people and sickened more than 700.